Understanding the more complicated features of parallel structure can help you on graduate level exams such as the GRE and GMAT. Advanced parallel structure is also useful for academic writing at American universities. This is especially true in upper-level bachelor classes and grad school.

Review of Basic Rules for Parallel Structure in English

Before we get to the advanced rules in parallel structure, let’s look at the four basic rules I introduced in the last post:

Rule 1: Parallel structure requires that verbs or nouns have the same grammar form.Generally, parallel structure applies to two or more verbs or two or more nouns. Think “walking and smiling,” not “walking and to smile.” Or think “a cat and a dog,” not “the cat and a dog.”

Rule 2: Parallel structure should be used within a single clause.A clause is a subject and predicate. A clause can be a complete sentence. (The sun rises in the east.) Or it can be part of a larger sentence. (We watched the sun rise in the east.) When there are multiple verbs within a clause, they should demonstrate parallel structure by having the same grammar for each verb. (The sun will rise in the east and shine brightly at noon.) The same is true for multiple nouns in a sentence. (The sun’s rays and the moon’s beams shine at different times.)

Rule 3: Conjunctions are a sign that you might need parallel structure.Conjunctions are words that join multiple verbs, multiple nouns, or multiple clauses. Common conjunctions include and, but,while, and because. For a longer list of conjunctions, see Kate’s post about using conjunctions on the TOEFL. When verbs or nouns are joined by conjunctions, they may need to be parallel. Examples include “driving while eating” (a bad idea!), or “many flowers and many bees.”

Rule 4: Parallel structure should only be broken for specific reasons.There are a number of specific situations where you can break parallel structure. Most of these situations involve changes in verb tense because events have different durations or different time frames… or changes in noun form to contrast two nouns as being very different. You can see specific examples of non-parallel verbs in the previous post or in my post about past tenses. My previous post on parallel structure in English also has examples of acceptable breaks in parallel structure for nouns.

Advanced rules for parallel structure in English

There are a few more complicated rules for parallel structure in English. Again, these rules aren’t necessary for TOEFL prep, but can be useful on more advanced exams and academic tasks.

Advanced parallel structure, Rule A: Parallel structure usually isn’t needed in two different clauses in a sentence.

Often, it may look like a sentence breaks parallel structure, with one grammar form at the beginning of a sentence, and another at the end. But remember, parallel structure usually happens within just one clause. In a complex sentence, each clause may have its own grammar. Below is an example complex academic sentence with a change in grammar from one clause to the next.

Facts in a news story may come from places external to the news agency, where they may be gathered from witnesses and other primary sources.

The two clauses in that sentence are divided by a comma. Notice that in the first clause the verb “come from” is simple present tense. But in the second clause, “gathered” is past participle. This is perfectly OK because each clause has different grammar. The first clause mentions something that is done by facts. Facts come from somewhere. The second clause mentions something that is done to facts. So in the second clause, we need a passive voice form. And passive voice uses past participle verbs.

You may also notice that the sentence above is a little bit awkward and wordy. I added a few extra words to the second clause to make the subject of the clause clearer. In a real piece of academic writing, the sentence above would probably read like this:

Facts in a news story may come from places external to the news agency, gathered from witnesses and other primary sources.

In this shorter version of the sentence, the subject of the second clause is omitted but implied. This really makes the sentence look like it’s breaking the rules of parallel structure. But it’s not. In the shortened version, the second clause is a little bit “hidden” because the subject is implied but not stated. But there still is a subject and there still is a second clause.

Within each clause, parallel structure would be used if extra verbs or nouns were added. Here’s what that could look like:

Facts and quotations in a news story may come from places external to the news agency, where they may be taken or gathered from witnesses and other primary sources.

Here, the first clause has two plural nouns in parallel structure. A noun pair such as facts and a quotation would not be acceptable, unless there was a specific reason for one plural form and one singular form. (See General Rule 4 above.)

If a clause includes a prepositional phrase, the nouns and verbs in the prepositional phrase don’t necessarily need the same grammar as the nouns and verbs in the rest of the clause. Think of the prepositional phrase as a magical bubble where the rules or parallelism do not apply. (Who says grammar can’t be exciting?)

Below is an example of a sentence where the verb forms are different in the prepositional phrase and in the rest of the clause.

Mark Zuckerberg expanded Facebook’s business operations by setting up an additional California business office.

Here, we see the past tense verb “expanded” at the beginning of the clause, but we see the present participle verb “setting up” in the second half of the clause. As I’ve mentioned before, participle verbs can be used like nouns. And in this case, the act of “setting up” is used as the object of the preposition “by.”

Now remember in Advanced Rule 2 that a second clause can be “hidden” by leaving the subject of the clause unstated. In a complex sentence, you can also sometimes omit a preposition, so that a prepositional phrase is “hidden.” That looks like this:

Mark Zuckerberg expanded Facebook’s business operations, setting up an additional California business office.

And once more, we have a simplified sentence that looks like it might have bad parallel structure. But no rules have been broken. The prepositional phrase containing the seemingly non-parallel verb is still there. It’s just harder to see.

Advanced parallel structure, Rule C: Not every part of a parallel form needs to be repeated.

This advanced parallel structure rule is probably the hardest one to explain. But it’s the most common rule. You probably follow this rule all the time in regular English use without even knowing it.

Before I explain what I mean when I say not every form needs to be repeated, I’ll show you some simple examples. The sentence sets below mean the exact same thing:

Sentence Set I:

Mary went to the store and to the hospital. Mary went to the store and the hospital. Mary went to the store and hospital.

Sentence Set II:

Jack will graduate university and will look for a job.

Jack will graduate university and look for a job.

In the first sentence from Set I, “to the” is repeated in both parallel structures. In the second Set I sentence, only “the” is repeated. And in the third sentence in Set I, “to the” appears immediately before the first noun (store), but isn’t repeated before the second noun (hospital). Similarly, in Sentence Set II, will does not need to be repeated. Will can be used just once but applied to both of the verbs in the sentence, giving both verbs parallel future tense structure.

This rule applies to short, simple sentences. When a sentence gets longer or more complex, you need to repeat more parts of the parallel structure. Compare the two sentences below. The second sentence would be a lot more confusing if the whole structure weren’t repeated.

Jack will graduate university and look for a job.

After four years of university study at Stanford, Jack will proudly graduate university with a BFA, and at that point, he will look for a job.

Between this post and the last one, you should now have a pretty good handle on parallel structure. In an upcoming post, I’ll offer some review activities on this aspect of English grammar. Watch this blog!

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About David Recine

David is a test prep expert at Magoosh. He has a Bachelor of Social Work from the University of Wisconsin-Eau Claire and a Masters in Teaching English to Speakers of other Languages from the University of Wisconsin-River Falls. He has been teaching K-12, University, and adult education classes since 2007 and has worked with students from every continent. Currently, David lives in a small town in the American Upper Midwest. When he’s not teaching or writing, David studies Korean, plays with his son, and takes road trips to Minneapolis to get a taste of city life. Follow David on Google+ and Twitter!

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